The roadblocks went up on a Friday at several points in two Alabama towns, about 40 miles on either side of Birmingham.

For the next two days,
off-duty sheriff's deputies in St. Clair County, to the east, and Bibb
County, to the southwest, flagged down motorists and steered them toward
federal highway safety researchers. The researchers asked them a few
questions about drinking and drug use and asked them for breath, saliva
and blood samples -- offering them $10 for saliva and $50 to give blood.